Weight Stack Assembly for Exercise Machine

ABSTRACT

A weight stack for an exercise machine includes a plurality of weights arranged in a vertical stack. Each of the weights has a body portion with substantially parallel upper and lower surfaces and includes at least one open-ended, forwardly facing recess in the lower surface. Each of the recesses has a height and a width, with an aspect ratio of height divided by width being between about 0.06 and 0.375.

FIELD OF THE INVENTION

The present invention relates generally to exercise equipment, and relates more particularly to resistance systems for exercise equipment.

BACKGROUND OF THE INVENTION

Exercise devices, and in particular weight training machines, typically include a mechanical member that the user moves along a prescribed path for exercise. Conventionally, movement of the mechanical member is resisted in some fashion to render the movement more difficult and thereby intensify the exercise. The most common means for providing resistance to movement of the mechanical member is a unit that connects the mechanical member with one or more weights such that the weights are raised in response to the movement of the mechanical member.

Often the weights of an exercise machine are provided in a stack; any or all of the weights (which are typically identical in weight) can be secured to a connecting rod that extends through the entire weight, stack via apertures in the weights. The connecting member is then interconnected with the mechanical member, either directly or indirectly, via a one or more of belts, chains, cables, levers, or other means. Movement of the mechanical member by a user is resisted by the weight secured to the connecting rod.

In one commonly employed configuration, the weights are secured to the connecting rod via a selecting pin, which can be inserted through an aperture included in each weight or a gap between weights and into an opening in the connecting rod. Insertion of the connecting pin into a connecting rod aperture causes the portion of the weights in the stack above the pin (i.e., those weights positioned between the pin and the interconnecting belt) to travel as a substack with the connecting rod and thereby provide resistance to movement of the exercise arm; the portion of the weights in the stack below the pin (i.e., those weights positioned farther from the interconnecting belt than the pin) remain stationary and provide no resistance to movement of the exercise arm. Of course, the amount of weight providing resistance to the movement is equal to the weight of the substack of weights travelling with the connecting rod. The amount of resistive weight can be easily adjusted by repositioning the selecting pin in the connecting rod in a different weight or between different weights so that a different number of weights travel with the connecting rod.

Space limitations often restrict the number of weights that are included in a weight stack. Because it is desirable to provide exercise machines that can be comfortably used by virtually any user (which may include both weak or infirm individuals using the machine for rehabilitation and very strong individuals for whom substantial resistance is required), the weights typically provided are rather heavy. Also, generally the individual weights in a stack are of the same magnitude. As the weights in a stack are generally both heavy and uniform in magnitude, the incremental increase in resistance experienced by a user adding but a single weight to the travelling substack can be quite significant. Such an increase can be particularly onerous for novices, rehabilitation patients, elderly users, and others who lack strength.

One attempt to address the problem of an overly high incremental weight increase is offered in U.S. Pat. No. 4,834,365 to Jones. The Jones machine includes two weight stacks: one stack comprising conventional heavier weights; and one stack comprising much lighter weights. These stacks are positioned so that the stack of lighter weights resides directly above the stack of heavier weights. Both stacks share a common connecting rod to which a portion of their weights can be secured. When the mechanical member of the exercise machine is moved, the desired number of weights of both stacks travel with the connecting rod and provide resistance. The lighter weights contribute to the resistance experienced by the user and therefore provide more resistance magnitude options. For example, a rehabilitating patient may be exercising on a machine that has a large weight stack of twenty pound weights and a lighter weight stack of one pound weights. If the patient's rehabilitation is best served by a resistance of thirty pounds, he can add resistance in one pound increments with the lighter weight stack to a twenty pound weight from the heavier stack to total thirty pounds rather than being forced to proceed directly from twenty to forty pounds of resistance.

Another approach is discussed in U.S. Pat. No. 5,776,040 to Webb, which includes separate stacks of lighter (e.g., one-pound) and heavier (e.g., ten-pound) weights, each with its own connecting rod and pin. The weight stacks are positioned side-by-side. Each connecting rod is attached to its own belt, with the belts following similar paths over pulley assemblies that are coupled to a movement arm. By selecting weights from both weight stacks, the exerciser can select precisely an amount of weight desired for resistance.

In view of the foregoing, it may be desirable to provide additional weight systems that provide resistance in small increments.

SUMMARY OF THE INVENTION

As a first aspect, embodiments of the present invention are directed to a weight stack for an exercise machine. The weight stack comprises a plurality of weights arranged in a vertical stack. Each of the weights has a body portion with substantially parallel upper and lower surfaces and includes at least one open-ended, forwardly facing recess in the lower surface. Each of the recesses has a height and a width, with an aspect ratio of height divided by width being between about 0.06 and 0.25.

As a second aspect, embodiments of the present invention are directed to a weight stack assembly for an exercise machine, comprising: a plurality of weights arranged in a vertical stack, each of the weights having a body portion with substantially parallel upper and lower surfaces and including at least one open-ended, forwardly facing recess in the lower surface; a post extending through the plurality of weights, the post configured to connect with a movement arm of an exercise machine, the post including a column of oblong apertures that align with the recesses of the weights; and a selector unit with upper and lower prongs, the lower prong configured to be inserted into one of the recesses and one of the apertures of a first weight, and the upper prong configured to be inserted into one of the recesses and one of the apertures of a second weight, the second weight being disposed above the first weight in the weight stack. Insertion of the prongs selects a portion of the weights to provide resistance for exercise.

As a third aspect, embodiments of the present invention are directed to a weight for an exercise machine, comprising: a body portion with parallel upper and lower surfaces, opposed side edges, and opposed front and rear edges; a pair of open-ended slots extending from the front edge of the body portion; and an aperture located generally in the center of the body portion. The slots are connected with the aperture. The slots are off-center relative to the side edges of the body portion.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a weight stack for an exercise machine according to embodiments of the present invention.

FIG. 2 is a front view of the weight stack of FIG. 1.

FIG. 2A is an enlarged perspective view of the area “A” of FIG. 4.

FIG. 3 is a partially exploded perspective view of the weight stack of FIG. 1.

FIG. 4 is a perspective view of the selector fork employed with the weight stack of FIG. 1.

FIG. 5 is a side view of the weight stack of FIG. 1.

FIG. 6 is a bottom perspective view of a weight of the weight stack of FIG. 1.

FIG. 7 is a partial perspective view of the center post, selector fork and two weights of the weight stack of FIG. 1.

FIG. 8 is a partial perspective view of a selector fork, center post and weight according to embodiments of the present invention.

FIG. 9 is a perspective view of a weight stack for an exercise machine according to other embodiments of the present invention.

FIG. 10 is a front view of the weight stack of FIG. 1.

FIG. 10A is an enlarged perspective view of the area “A” of FIG. 4.

FIG. 11 is a partially exploded perspective view of the weight stack of FIG. 1.

FIG. 12 is a perspective view of the selector fork employed with the weight stack of FIG. 1.

FIG. 13 is a side view of the weight stack of FIG. 1.

FIG. 14 is a bottom perspective view of a weight of the weight stack of FIG. 1.

FIG. 15 is a partial perspective view of the center post, selector fork and two weights of the weight stack of FIG. 1.

FIG. 16 is a partial perspective view of a selector fork, center post and weight according to embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention will now be described more fully hereinafter, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.

Well-known functions or constructions may not be described in detail for brevity and/or clarity.

Referring now to the drawings, a weight stack assembly for an exercise machine, designated broadly at 10, is shown in FIGS. 1-7. The weight stack assembly 10 comprises a top weight 12 and a plurality of weights 20 arranged in vertically stacked relationship. The top weight 12 has a generally flat body 13. The top weight 12 is also attached to bushings 18 that surround guide rods (not shown) that help to guide the weight stack 10 as some or all of the weights 20 are raised vertically during exercise.

A center post 15 (best seen in FIG. 7) extends below the body 13 through the stacked weights 20, and also forms an attachment tab 14 that extends above the body 13 for attachment to a rope, cable or the like that is connected, either directly or indirectly, to a movement arm of an exercise machine. The center post 15 includes oblong holes 16 that are arranged in aligned fashion (see FIG. 7). In some embodiments, the holes 16 have an aspect ratio (height/width) of between about 0.06 and 0.25.

Each of the weights 20 is substantially identical to the other weights 20. As such, only one weight 20 is described in detail herein, with the understanding that the discussion is equally applicable to the other weights 20 also.

Referring now to FIG. 6, it can be seen that each of the weights 20 includes a generally flat body portion 21. An open-ended, forwardly- and downwardly-facing recess 22 extends from the front edge of the weight 20 to a centrally-located, generally rectangular post aperture 26, wherein the center post 15 is received, then further rearwardly from the post aperture 26. Each weight 20 also includes a pair of holes 24 that are aligned with the bushings 18 of the top weight to receive the guide rods of the system.

In some embodiments, the weights 20 are relatively thin. In certain embodiments, the weights 20 are between about ¼ or ⅜ inch to ⅝ or ¾ inch in thickness; in some embodiments they may be as thick as ⅜ to ½ inch. In some embodiments, the weights 20 are five pound weights, although any magnitude can be employed with the present invention. The recess 22 typically has an aspect ratio (i.e., the ratio of the width of the recess 22 to the height of the recess 22) of between about 0.06 and 0.375, which may be beneficial if the weights 22 are indeed thin.

As can be seen in FIGS. 1-3 and 5, the weights 20 are arranged in vertically stacked fashion, with the recess 22 of each weight 20 being positioned to align with “column” of holes 16 of the center post 15 (this is best seen in FIG. 2). Also, each weight 20 is of a thickness such that, when arranged in a vertical stack as shown in FIGS. 1-3 and 5, the weight 20 is level with one of the holes 16. As a result, each of the holes 16 can be accessed through one of the recess 22.

A selector fork 30 is shown in FIG. 4. The selector fork 30 includes upper and lower flattened prongs 32 a, 32 b that extend from a head 34. A pointer 36 extends from the head 34 on one side near the lower prong 32 b. In some embodiments, the upper and lower prongs 32 a, 32 b have an aspect ratio of between about 0.06 and 0.25. As an example, the prongs 32 a, 32 b may have a height of about 0.125 to 0.25 inch and a width of about 0.75 to 1.25 inches.

As shown in FIGS. 1-3 and 5, the selector fork 30 can be inserted into the weights 20 by orienting the head 34 so that the prongs 32 a, 32 b are vertically aligned. In this orientation, the prongs 32 a, 32 b can be received within respective recess 22 of two weights 20′, 20″ that are separated by a third weight 20′″. Once in the recess 22, the prongs 32 a, 32 b are inserted into the holes 16 of the center post 15 that correspond to those particular slots 22. In this position, the lower prong 32 b will underlie the weight 20″ immediately above it and support it from underneath (see FIGS. 5 and 7).

In selecting a particular resistance for exercise, the exerciser should insert the selector fork 30 so that the recess 22 of the lower weight 20″ receives the lower prong 32 b represents the desired resistance. For example, in FIGS. 2 and 2A, the upper weight 20′ is designated “115”, the lower weight 20′ is designated “120”, and the middle weight 20″ therebetween is designated “120”; the resistance that would be provided by such insertion would be the 125 pounds of the lower weight 20″. As can be seen in FIG. 2A, the pointers 36 is positioned to point to the lower weight 20″ upon insertion of the selector fork 30 into the recesses 22, thereby clearly indicating to the exerciser the magnitude of the resistance.

As the exerciser manipulates a movement arm (and, in turn, raises the center post 15) during exercise, the magnitude of resistance is determined by the number of weights 20 selected via the selector fork 30 to rise with the center post 15. As can be discerned from FIGS. 1-3 and 5, the lower prong 32 b fits within the recess 22 of the lower weight 20″ and immediately below the body portion 21 of the lower weight 20″. Because the lower prong 32 b supports the lower weight 20″ from underneath, raising of the center post 15 via movement of the movement arm lifts the lower weight 20″ and the weights 20 above it, thereby providing resistance to the movement of the movement arm; the weights 20 below the lower weight 20″ do not travel upwardly with the center post 15.

The thin profile of the prongs 32 a, 32 b of the selector pin 30 can enable the use of thinner (and thus lighter) weights 20 than are typically employed for weight stacks of this type. As a result, the degree of resistance for exercise can be more precisely selected even though the weight stack may occupy the same volume as in prior machines.

FIG. 8 illustrates a differently configured selector fork 50. The selector fork 50 includes a single prong 52 that extends from a head 54. A pointer 56 extends from the head 54. In selecting a particular resistance for exercise, the exerciser should insert the selector fork 50 so that the weight 20 that receive the selector fork prong 52 within its recess 22 represents the desired resistance. The pointer 56 points to that particular weight 20.

Another embodiment of a weight stack assembly for an exercise machine, designated broadly at 10, is shown in FIGS. 9-15. The weight stack assembly 110 comprises a top weight 112 and a plurality of weights 120 arranged in vertically stacked relationship. Like the top weight 12 described above, the top weight 112 has a generally flat body 113 and is also attached to bushings 118 that surround guide rods (not shown) that help to guide the weight stack 110 as some or all of the weights 120 are raised vertically during exercise.

A center post 115 (best seen in FIG. 15) extends below the body 113 through the stacked weights 20, and also forms an attachment tab 114 that extends above the body 113 for attachment to a rope, cable or the like that is connected, either directly or indirectly, to a movement arm of an exercise machine. Unlike the center post 15, the center post 115 includes two sets of open-ended oblong apertures 116 a, 116 b along its side edges. In some embodiments, the apertures 16 have an aspect ratio (height/width) of between about 0.125 and 0.25.

Each of the weights 120 is substantially identical to the other weights 120. As such, only one weight 120 is described in detail herein, with the understanding that the discussion is equally applicable to the other weights 120 also.

Referring now to FIG. 14, it can be seen that each of the weights 120 includes a generally flat body portion 121. Two open-ended, forwardly- and downwardly-facing recesses 122 a, 122 b extend from the front edge of the weight 120 to a centrally-located, generally rectangular post aperture 126, wherein the center post 115 is received, then further rearwardly from the post aperture 126. The recesses 122 a, 122 b are offset from the center of the body portion 121 toward the side edges thereof. Each weight 20 also includes a pair of holes 124 that are aligned with the bushings 118 of the top weight to receive the guide rods of the system.

In some embodiments, the weights 120 are relatively thin. In certain embodiments, the weights 120 are between about ¼ or ⅜ inch to ⅝ or ¾ inch in thickness; in some embodiments they may be as thick as ⅜ to ½ inch. In some embodiments, the weights 120 are five pound weights, although any magnitude can be employed with the present invention. The recesses 122 a, 122 b typically have an aspect ratio (i.e., the ratio of the width of the recess 122 a, 122 b to the height of the recess 122 a, 122 b) of between about 0.06 and 0.375, which may be beneficial if the weights 120 are indeed thin.

As can be seen in FIGS. 9-11 and 13, the weights 120 are arranged in vertically stacked fashion, with the recesses 122 a, 122 b of each weight 120 being positioned to align with the “columns” of apertures 116 a, 116 b of the center post 115 (this is best seen in FIG. 10). Also, each weight 120 is of a thickness such that, when arranged in a vertical stack as shown in FIGS. 9-11 and 13, the weight 120 is level with one pair of the apertures 116 a, 116 b. As a result, each of the apertures 116 a, 116 b can be accessed through one of the recesses 122 a, 122 b.

A selector fork 130 is shown in FIG. 11. The selector fork 30 includes two flattened upper prongs 132 a, 132 b and two flattened lower prongs 133 a, 133 b that extend from a head 134. A pointer 136 extends from the head 134 on one side near the lower prong 133 b. In some embodiments, the upper and lower prongs 132 a, 132 b, 133 a, 133 b have an aspect ratio of between about 0.125 and 0.25. For example, the prongs 32 a, 32 b, 33 a, 33 b may have a height of between about 0.125 to 0.25 inch and a width of between about 0.5 to I inch.

As shown in FIGS. 9-11 and 13, the selector fork 130 can be inserted into the weights 120 by orienting the head 34 so that the upper prongs 132 a, 132 b are vertically aligned with the lower prongs 133 a, 133 b. In this orientation, the upper prongs 132 a, 132 b can be received within respective recesses 122 a, 122 b of a first weights 120′, and the lower prongs 133 a, 133 b can be received within respective recesses 122 a, 122 b of a second weight 120″. The first and second weights 120′, 120″ are separated by a third weight 120′″. Once in the recesses 122 a, 122 b, the prongs 132 a, 132 b, 133 a, 133 b are inserted into the apertures 116 a, 116 b of the center post 115 that correspond to those particular recesses 122 a, 122 b. In this position, the lower prongs 133 a, 133 b will underlie the weight 120″ immediately above them and support the weight 120″ from underneath.

In selecting a particular resistance for exercise, the exerciser should insert the selector fork 30 so that the lower weight 120″ receives the lower prongs 133 a, 133 b represents the desired resistance. For example, in FIG. 10A, the upper weight 120′ is designated “115”, the lower weight 120″ is designated “125”, and the middle weight 120′″ therebetween is designated “120”; the resistance that would be provided by such insertion would be the 125 pounds of the lower weight 120″. As can be seen in FIG. 10A, the pointer 136 is positioned to point to the lower weight 120″ upon insertion of the selector fork 130 into the recesses 122 a, 122 b of the lower weight 120″, thereby clearly indicating to the exerciser the magnitude of the resistance.

As with the weight stack 10, as the exerciser manipulates a movement arm (and, in turn, raises the center post 115) during exercise, the magnitude of resistance is determined by the number of weights 120 selected via the selector fork 130 to rise with the center post 115. As can be discerned from FIG. 8, the lower prongs 133 a, 133 b fit within the recesses 122 a, 122 b of the lower weight 120″ and immediately below the body portion 121 of the lower weight 120″. Because the lower prongs 133 a, 133 b support the lower weight 120″ from underneath, raising of the center post 115 via movement of the movement arm lifts the lower weight 120″ and the weights 120 above it, thereby providing resistance to the movement of the movement arm; the weights 120 below the lower weight 120″ do not travel upwardly with the center post 115.

As was the case with the lower prong 32 b discussed above, the thin profile of the prongs 133 a, 133 b of the selector pin 130 can enable the use of thinner (and thus lighter) weights 120 than are typically employed for weight stacks of this type. As a result, the degree of resistance for exercise can be more precisely selected even though the weight stack may occupy the same volume as in prior machines.

FIG. 16 illustrates the weight stack 110 utilizing a differently configured selector fork 150. The selector fork 150 includes two prongs 152 a, 152 b that extend from a head 154. A pointer 156 extends from the head 54. In selecting a particular resistance for exercise, the exerciser should insert the selector fork 150 so that the weight 120 that receives the selector fork prongs 152 a, 152 b within its recesses 122 a, 122 b represents the desired resistance. The pointer 56 points to that particular weight 120. The prongs 152 a, 152 b are received in the corresponding apertures 116 a, 116 b of the center post 115.

Those skilled in this art will recognize that, although the weights 20, 120 are illustrated as being 5 pound weights, weights of a different magnitude (e.g., 10 pound weights) may also be used. Also, the weights 20, 120 are shown as being generally rectangular in shape, but may take other shapes (e.g., circular, oval, or triangular) as desired.

Other variations from the illustrated embodiments are also contemplated. For example the center posts 15, 115 may take a different cross-sectional shape, or in some embodiments two separate, parallel center posts may be employed. Also, selector units other than the selector pin and selector forks may be employed. Further deviations from that illustrated and explicitly described may also be employed.

It should also be noted that the weight stack assemblies 10, 110 may be employed with a variety of exercise machine types. For example, the weight stack assemblies 10, 110 may be employed with: machines for leg exercise, such as leg curl, leg press, and calf machines; machines for hip exercise, such as hip abduction, adduction, and abduction/adduction machines, machines for neck exercise, such as 4-way neck, behind neck, and neck and shoulders machines; machines for the upper torso, such as 10-degree and 50-degree chest, chest and double chest, declined and inclined press, bench press, reverse and super pullover, torso arm, seated dip, rowing back, and compound row machines; machines for the mid-torso, such as abdominal, lower abdominal, rotary torso, and low back machines; machines for the arms, such as multi-biceps, multi-triceps, and super forearm machines; and machines for the shoulders, such as lateral raise, overhead press, and rotary shoulder machines.

The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein. 

1. A weight stack for an exercise machine, comprising: a plurality of weights arranged in a vertical stack, each of the weights having a body portion with substantially parallel upper and lower surfaces and including at least one open-ended, forwardly facing recess in the lower surface, each of the recesses having a height and a width, and wherein an aspect ratio of height divided by width is between about 0.06 and 0.375.
 2. The weight stack defined in claim 1, wherein each of the weights includes an aperture connected with its recess, the aperture configured to receive a center post.
 3. The weight stack defined in claim 2, wherein the recess extends rearwardly beyond the aperture.
 4. The weight stack defined in claim 3, wherein the aperture of each weight is located generally in the center of the weight.
 5. The weight stack defined in claim 1, wherein the weights are between about ¼ and ¾ inch in thickness.
 6. The weight stack defined in claim 1, wherein the at least one recess is two recesses.
 7. The weight stack defined in claim 6, wherein each of the weights includes an aperture connected with its recess, the aperture configured to receive a center post.
 8. The weight stack defined in claim 7, wherein the recess extends rearwardly beyond the aperture.
 9. A weight stack assembly for an exercise machine, comprising: a plurality of weights arranged in a vertical stack, each of the weights having a body portion with substantially parallel upper and lower surfaces and including at least one open-ended, forwardly facing recess in the lower surface; a post extending through the plurality of weights, the post configured to connect with a movement arm of an exercise machine, the post including a column of oblong apertures that align with the recesses of the weights; and a selector unit with upper and lower prongs, the lower prong configured to be inserted into one of the recesses and one of the apertures of a first weight, and the upper prong configured to be inserted into one of the recesses and one of the apertures of a second weight, the second weight being disposed above the first weight in the weight stack, insertion of the prongs selecting a portion of the weights to provide resistance for exercise.
 10. The weight stack assembly defined in claim 9, wherein the selector unit includes a single upper prong and a single lower prong.
 11. The weight stack assembly defined in claim 10, wherein the selector unit further comprises an indicator that designates the weight immediately above the lower prong.
 12. The weight stack assembly defined in claim 10, wherein the at least one recess is generally centered between side edges of the weight.
 13. The weight stack assembly defined in claim 9, wherein the at least one recess of each weight is two recesses, and wherein the selector unit includes a pair of upper prongs and a pair of lower prongs.
 14. The weight stack assembly defined in claim 12, wherein the selector unit further comprises an indicator that designates the weight immediately above the lower prong.
 15. The weight stack assembly defined in claim 13, wherein each of the recesses is slightly offset from center between side edges of the weight.
 16. The weight stack assembly defined in claim 9, wherein the apertures of the center post are closed-ended apertures.
 17. The weight stack assembly defined in claim 9, wherein the apertures of the center post are open ended apertures located on the side edges of the center post.
 18. The weight stack assembly defined in claim 9, wherein the weights are between about ¼ and ¾ inch in thickness.
 19. A weight for an exercise machine, comprising: a body portion with parallel upper and lower surfaces, opposed side edges, and opposed front and rear edges; a pair of open-ended slots extending from the front edge of the body portion; and an aperture located generally in the center of the body portion; wherein the slots are connected with the aperture; and wherein the slots are off-center relative to the side edges of the body portion.
 20. The weight defined in claim 19, wherein the aperture is generally rectangular.
 21. The weight defined in claim 19 having a thickness of between about ¼ and ¼ inch. 